The use of an O2 sensor to sense the amount of O2 in the exhaust of an automobile or other motor vehicle and to send sensor signals to an electronic control unit or module (ECU) also incorporated in the motor vehicle is well known. The terms “electronic control unit”, “module”, “electronic control module” and “ECU” are interchangeable as employed herein. The ECU is associated with the fuel injector system of the engine to control the air/fuel mixture introduced into the engine cylinders. With the fuel system in closed loop operation after the O2 sensor warms up, the O2 sensor voltage cycles up and down. This cycling (which varies in speed between idling and cruising) occurs because the ECU senses the O2 voltage and then changes the pulse width of the signal driving the fuel injector on and off. This switching action allows the ECU to perform minor adjustments to the air/fuel ratio to allow the catalytic converter to perform its job to optimize the “oxidation” of carbon monoxide and hydrocarbons as well as the reduction of nitrogen oxides. The oxidation occurs when the mixture is slightly lean and more oxygen is available, and the reduction occurs when the mixture is slightly rich and less oxygen is available.
It is known to modify the function of an existing electronic control unit or module (ECU) by physically changing the functional parameters of the programmable eprom or computer chip, or changing the existing eprom itself inside the ECU, in an attempt to improve engine performance.
Various problems can arise when an existing ECU is modified as indicated above. The physically changed or new eprom must be specific to a manufacturer's application, and during use it may cause knocking, lean misfires, uncontrolled parameters during timed sequences and the signaling of alarming trouble codes in vehicles with on-board diagnostic (OBD) systems.
My U.S. Pat. No. 6,260,547, issued Jul. 17, 2001, discloses use of a controller interposed between an O2 sensor and a preprogrammed electronic control unit employed in the motor vehicle to provide a richer fuel mixture than would normally be the case and thus boost the performance of the engine.
The following United States patents and foreign patent documents are cited in U.S. Pat. No. 6,260,547: U.S. Pat. No. 5,836,153, issued Nov. 17, 1998, U.S. Pat. No. 5,777,204, issued Jul. 7, 1998, U.S. Pat. No. 4,479,464, issued Oct. 30, 1984, U.S. Pat. No. 4,202,301, issued May 13, 1980, U.S. Pat. No. 5,033,438, issued Jul. 23, 1991, U.S. Pat. No. 5,251,604, issued Oct. 12, 1993, British Patent No. 2,077,962, dated December, 1981 and British Patent No. 2,093,228, Granted August, 1982.
The invention disclosed in my U.S. Pat. No. 6,260,547 alters the O2 sensor signal voltage to the ECU. The ECU responds to this altered signal by widening the pulse width to the injectors thereby enriching the air/fuel ratio during the combustion process. The ECU has a fuel map which has pre-determined fuel values which are influenced by factors such as RPM, manifold absolute pressure (MAP), engine temperature, intake air temperature, and throttle position. These fluctuating parameters or variable operational factors relating to the operation of the internal combustion engine influence the points on the map that the ECU uses to send out a predetermined electrical pulse width to open the fuel injectors which is then fine tuned by the corrective signal from the O2 sensor to a pre-set air/fuel ratio.
In the arrangement disclosed in U.S. Pat. No. 6,260,547, the O2 sensor signal is altered a specific or pre-set percentage (depending on the enrichment setting used) throughout the entire ECU fuel map without adjusting for fluctuating manifold absolute pressure or other of the above-indicated influences. As a result, the percentage of enrichment by current technology remains fixed whether the ECU map is influenced by additional parameters as stated above or not. Because these additional variable operational factors relating to the operation of the internal combustion engine continuously change and influence the ECU's fuel map when responding to the O2 sensor signal, a minor fluctuation occurs in the specific air/fuel ratio as pre-set.